Loans and Allowance for Loan Losses, Allowance for Loan Losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		$ 44,503	$ 44,162	$ 44,170	$ 43,890
Loans charged off [Abstract]
Total loan charge offs		172	847	660	2,103
Recoveries of loans previously charged off [Abstract]
Total recoveries		105	217	326	595
Net loans charged off (recoveries)		67	630	334	1,508
Provision (recoveries) for loan losses		300	550	900	1,700
Balance at end of period		44,736	44,082	44,736	44,082
New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	163	812	645	1,917
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	104	145	322	523
Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		9	35	15	186
Recoveries of loans previously charged off [Abstract]
Total recoveries		1	72	4	72
Commercial [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		4,195	4,596	4,324	4,929
Loans charged off [Abstract]
Total loan charge offs		0	0	0	72
Recoveries of loans previously charged off [Abstract]
Total recoveries		2	0	9	8
Net loans charged off (recoveries)		(2)	0	(9)	64
Provision (recoveries) for loan losses		(65)	24	(201)	(245)
Balance at end of period		4,132	4,620	4,132	4,620
Commercial [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	0	0	0	72
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	2	0	9	8
Commercial [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		0	0	0	0
Recoveries of loans previously charged off [Abstract]
Total recoveries		0	0	0	0
Real Estate Mortgage - 1 to 4 Family [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		39,471	38,871	39,077	38,231
Loans charged off [Abstract]
Total loan charge offs		94	778	464	1,866
Recoveries of loans previously charged off [Abstract]
Total recoveries		97	209	289	566
Net loans charged off (recoveries)		(3)	569	175	1,300
Provision (recoveries) for loan losses		227	434	799	1,805
Balance at end of period		39,701	38,736	39,701	38,736
Real Estate Mortgage - 1 to 4 Family [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	94	747	464	1,699
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	97	137	289	494
Real Estate Mortgage - 1 to 4 Family [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		0	31	0	167
Recoveries of loans previously charged off [Abstract]
Total recoveries		0	72	0	72
Installment [Member]
Allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period		837	695	769	730
Loans charged off [Abstract]
Total loan charge offs		78	69	196	165
Recoveries of loans previously charged off [Abstract]
Total recoveries		6	8	28	21
Net loans charged off (recoveries)		72	61	168	144
Provision (recoveries) for loan losses		138	92	302	140
Balance at end of period		903	726	903	726
Installment [Member] | New York and Other States [Member]
Loans charged off [Abstract]
Total loan charge offs	[1]	69	65	181	146
Recoveries of loans previously charged off [Abstract]
Total recoveries	[1]	5	8	24	21
Installment [Member] | Florida [Member]
Loans charged off [Abstract]
Total loan charge offs		9	4	15	19
Recoveries of loans previously charged off [Abstract]
Total recoveries		$ 1	$ 0	$ 4	$ 0

[1] Includes New York, New Jersey, Vermont and Massachusetts.